DEVELOPMENT OF PLANTS 



279 



becomes greatly thickened on its outer and usually on its inner 

 walls. This layer of cells is firmly attached to the walls of the 

 capsule by rather short thick-walled cells (Figs. 210, 3, p; 211, 

 6-8, p). When the spores are mature, the more delicate cells 

 break down, leaving little more than a loose mass of spores and 

 the peristome within the capsule. The cells of the peristome 

 break apart into teeth-like segments (Fig. 211, 7) and being 



Fig. 211. Structure of capsule of Funaria: 5, capsule with calyptra, 5A, 

 removed. 6, section of nearly mature capsule— sp, spore-forming cells 

 surrounded on outside by loosely arranged chlorophyll-bearing cells; 0, 

 operculum; r, annulus; p, peristome; a, apophysis. 8, magnified view of 

 a portion of the capsule, showing the annulus, r, and the thick-walled cells 

 of the peristome, p, which are attached at their base to the epidermis by 

 a double row of cells ; sp, spore-forming cells. 7, the cells shown in 8, p, 

 have split apart, thus forming the inner and outer teeth-like segments of 

 the peristome.— After Sachs. 



